1. Field of the Invention
The invention relates to stent delivery systems, which are used to implant a stent into a patient's body lumen to maintain the patency thereof. More particularly, the present invention relates to a stent delivery sheath that is mounted over a catheter for deploying a stent in a body lumen.
2. Description of Related Art
Stents are generally cylindrically-shaped devices which function to hold open and sometimes expand a segment of a blood vessel or other body lumen. They are particularly suitable for use to support and hold back a dissected arterial lining which can occlude the fluid passageway. Stents also are useful in maintaining the patency of a body lumen, such as a coronary artery, after a percutaneous transluminal coronary angioplasty (PTCA) procedure or an atherectomy procedure to open a stenosed area of the artery. Several interventional treatment modalities are presently used for heart disease, including balloon and laser angioplasty, atherectomy, and bypass surgery.
In typical balloon angioplasty procedures, a guiding catheter having a preformed distal tip is percutaneously introduced through the femoral artery into the cardiovascular system of a patient in a conventional Seldinger technique and advanced within the cardiovascular system until the distal tip of the guiding catheter is seated in the ostium of a desired coronary artery. A guidewire is positioned within an inner lumen of a dilatation catheter, and then both are advanced through the guiding catheter to the distal end thereof. The guidewire is advanced out of the distal end of the guiding catheter into the patient's coronary vasculature until the distal end of the guidewire crosses a lesion to be dilated. Then, the dilatation catheter, having an inflatable balloon on the distal portion thereof, is advanced into the patient's coronary anatomy over the previously-introduced guidewire until the balloon of the dilation catheter is properly positioned across the lesion. Once in position across the lesion, the balloon, which is typically made of relatively non-distensible materials, is inflated to a predetermined size with liquid at relatively high pressure (e.g., greater than 4 atmospheres) to compress the arteriosclerotic plaque of the lesion against the inside of the artery wall and to otherwise expand the inner lumen of the artery. The dilatation balloon is then deflated so that blood flow can be resumed through the dilated artery and the dilatation catheter can be removed. Further details of dilatation catheters, guidewires, and devices associated therewith for angioplasty procedures can be found in U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lindquist); U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); U.S. Pat. No. 4,616,652 (Simpson); U.S. Pat. No. 4,638,805 (Powell); U.S. Pat. No. 4,748,982 (Horzewski et al.); U.S. Pat. No. 5,180,368 (Garrison); U.S. Pat. No. 5,458,613 (Gharibadeh et al.); and U.S. Pat. No. 5,496,346 (Horzewski et al.), which are hereby incorporated herein in their entirety by reference thereto.
A major problem that can occur during balloon angioplasty procedures is the formation of intimal flaps that can collapse and occlude the artery when the balloon is deflated at the end of the angioplasty procedure. Another major problem characteristic of balloon angioplasty procedures is the large number of patients which are subject to restenosis in the treated artery. In the case of restenosis, the treated artery may again be subject to balloon angioplasty or to other treatments such as bypass surgery, if additional balloon angioplasty procedures are not warranted. However, in the event of a partial or total occlusion of an artery resulting from the collapse of a dissected arterial lining after the dilatation balloon is deflated, the patient may require immediate medical attention, particularly where the occlusion occurs in a coronary artery.
A major focus of recent development work in the treatment of heart disease has been directed to endoprosthetic devices called stents. Stents are generally cylindrically-shaped intravascular devices that are placed within a damaged artery to hold it open. Such devices can be used to reduce the development of restenosis or to tack up an intimal flap to maintain the patency of the blood vessel immediately after intravascular treatments such as a PTCA.
Various means have been described to deliver and implant stents. One method frequently described for delivering a stent to a desired intraluminal location includes mounting the expandable stent on an expandable member, such as a balloon, provided on the distal end of an intravascular catheter, advancing the catheter to the desired location within the patient's body lumen, inflating the balloon on the catheter to expand the stent into a permanent expanded condition, and then deflating the balloon and removing the catheter.
However, the rapid and effective delivery of a stent to the desired location within a patient's vasculature is difficult and time consuming, particularly where stent deployment is accompanied by a balloon angioplasty procedure or where multiple stents are deployed in the body lumen.
It may therefore be important to improve existing stent delivery systems to provide rapid stent delivery while at the same time allowing a surgeon to select a desired stent and catheter combination. The present invention satisfies these needs.